A liquid crystal display device has been conventionally used in various kinds of electronic apparatuses such as a television, a notebook computer (personal computer), a desktop personal computer, a PDA (Personal Digital Assistant) and a portable phone. This is because the liquid crystal display device (i) is thinner and lighter than a CRT (Cathode Ray Tube) and (ii) can be driven with a lower operation voltage so as to have low power consumption.
A transflective type LCD device among liquid crystal display devices has two display modes, i.e., a transmission mode and a reflection mode, and can turn off a backlight in accordance with brightness of its surrounding environment. This allows a reduction in power consumption. Therefore, a transflective type LCD device is suitable for a personal digital assistant such as a portable phone.
On the other hand, it is increasingly becoming popular to display a moving image on a liquid crystal panel such as a liquid crystal television. This necessitates an increase in response speed of the liquid crystal panel so that the moving image can be displayed well. In view of the circumstances, it is an OCB mode (Optically Self-Compensated Birefringence mode) having high-speed response that has been recently attracting attention. In this OCB mode, a liquid crystal layer is sandwiched between two substrates. Each of the substrates is subjected to an alignment process which causes liquid crystal molecules to be aligned in parallel to each other and in the same direction. A wave plate is provided on a surface of each of the two substrates. A polarizing plate is further provided on each of the two substrates so that a crossed Nicols state is realized. A negative wave plate whose main axis is hybrid-aligned is used as the wave plate.
FIGS. 28 and 29 are cross-sectional views each schematically illustrating an arrangement of a conventional liquid crystal display device 101 using an OCB mode, FIG. 28 shows a state obtained in a case where no voltage is applied, and FIG. 29 shows a state obtained in a case where a voltage is applied.
As shown in FIGS. 28 and 29, a liquid crystal panel 105 in the liquid crystal display device 101 has an arrangement in which (i) a color filter substrate 141 in which a first transparent electrode 156 and a color filter (not shown) are formed on a first glass substrate 152 and (ii) a TFT substrate 142 in which a TFT (Thin Film Transistor) 133, a wiring layer (not shown), an insulating layer 126, and a second transparent electrode 122 are formed on a second glass substrate 151 are included, and in which a liquid crystal layer 155 including liquid crystal molecules 190 is sandwiched between the color filter substrate 141 and the TFT substrate 142.
As shown in FIGS. 28 and 29, according to the liquid crystal display device 101 using the OCB mode, the liquid crystal molecules 190 has a spray alignment when no voltage is applied (see FIG. 28), and the spray alignment is shifted to a bend alignment when a voltage is applied (see FIG. 29). An image is displayed during the bend alignment.
Patent Document 1 discloses a technique in which the OCB mode is applied to a transflective type LCD device.
FIG. 30 is a cross-sectional view schematically illustrating an arrangement of a liquid crystal display device of the Patent Document 1.
As shown in FIG. 30, according to the liquid crystal display device of the Patent Document 1, the liquid crystal molecules 190 in each of reflective areas a (g area in FIG. 30) are aligned like a half of the liquid crystal molecules 190 in a transmissive area b (f-area in FIG. 30). That is, the liquid crystal molecules 190 in each of the reflective areas a are vertically aligned at one end, and are horizontally aligned at the other end.
A step resin layer 154 on which a reflective electrode 123 is provided is formed in each of the reflective areas a of the TFT substrate 142. The step resin layer 154 causes a liquid crystal layer, which contributes to transmissive display, to become approximately two times thicker than a liquid crystal layer which contributes to reflective display, thereby resulting in that a light path length in the transmissive area is the same as that in the reflective area.
[Patent Document 1]
Japanese Unexamined Patent Application Publication Tokukai No. 2005-84593 (published on Mar. 31, 2005)
[Patent Document 2]
Japanese Unexamined Patent Application Publication Tokukai No. 2002-207206 (published on Jul. 26, 2002)
[Patent Document 3]
Japanese Unexamined Patent Application Publication Tokukai No. 2002-350902 (published on Dec. 4, 2002)
[Patent Document 4]
Japanese Unexamined Patent Application Publication Tokukai No. 2005-31680 (published on Feb. 3, 2005)
[Patent Document 5]
Japanese Patent No. 3334714 (published on Oct. 15, 2002)